The mission of the Washington University DDRCC is to advance research on the pathophysiology and host-environment interactions in digestive diseases. The Advanced Imaging and Tissue Analysis Core (AITAC) provides state-of-the-art histologic, immunohistochemical, tissue imaging and image analysis for studies of human Gl and jiver disease and animal-based digestive disease models. AITAC personnel have extensive expertise in morphologic analysis and imaging of digestive tissues. In the past funding period, the AITAC has provided comprehensive histologic and immunohistochemical support, advanced microscopic imaging and image analysis services and will continue to support 49 Full and 11 Associate DDRCC members in an efficient and highly cost-effective manner, consistent with our mission. The AITAC has two Components. The Tissue Analysis Component performs animal and human tissue embedding, sectioning, staining, and immunohistochemical analyses, and provides training in all services. The Advanced Image Analysis Component provides access to and training in routine light, fluorescent and inverted fluorescent microscopy, quantitative image analysis, in vivo imaging utilizing an investigator-built 2- photon microscope with complete image support for live cell and in vivo organ and tissue imaging, and electron microscopy (EM) with a full range of transmission EM services. The Specific Aims are: 1. To provide highly cost-effective, comprehensive tissue analysis services and investigator training in an extensive array of histologic procedures, including human and research animal tissue processing, embedding, routine and special staining and immunohistochemical analyses. 2. To provide access to and training in the use of advanced imaging and image analysis tools such as the Zeiss Axiovert with Apotome apparatus. Nuance imaging system, Zeiss and InForm image analysis software, and 2-photon microscopy for in vivo, live imaging (Advanced Image Analysis Component).